Induction heater



Sept. 10, 1.946. LQFGREN 2,407,562

INDUCTION HEATER Filed Aug. 17, 1942 fizz/anion Em 6. Zofgrerz Patented Sept. 10, 1946 UNITED STATES PATENT OFFICE INDUCTION HEATER Einar G. Lofgren, Minneapolis, Minn. Application August 17, 1942, Serial No. 455,053

2 Claims.

My present invention provide a simple and highly efficient induction heater; and, generally stated, consists of the novel devices, combination of devices, and arrangement of parts hereinafter described and defined in the claims.

Broadly considered, the heater is adapted for use to heat flowing fluids, either air or liquids, but is particularly designed and intended for use as an airflow heater. The immediate object of the present invention i the provision of a simple and efiicient device for heating small air spaces, such as airplane cabins, aviators garments, and the like.

A preferred commercial form of the heater is illustrated in the accompanying drawing wherein like characters indicate like parts throughout the several views.

Referring to the drawing:

Fig. 1 is a view in axial section showing the improved heater;

Fig. 2 is a transverse section taken on the line 2-2 of Fig. 1; and

Fig. 3 is a transverse section taken on the line 33 of Fig. 1.

Of the parts of the heater, the numeral II] indicates a cylindrical drum-like shell, preferably of sheet metal, provided with heads H and I2. Within the outer shell I is a smaller interme-' diate drum-like shell l3, also preferably of sheet metal, and of cylindrical form, provided with heads [4 and I5. The head [4 is rigidly connected to the head II by a tubular hub or sleeve Hi. The head I5 is rigidly connected to the head l2 by an axially located spacing stud or hub IT.

The intermediate shell [3 is spaced from the shell ID to form annular air space It. The head I4 is spaced from the head H to form an air intake chamber [9; and the head 15 is spaced from the head I2 to form an air chamber 20. The space at the upper or outlet end of the shell I3 is spanned by a baffle plate 2| having circumferentially spaced air pockets or passages 22. The head IS, in a similar manner, has circumferentially spaced air perforations or passages 23. The cold air inlet tube 24 opens into the air chamber l9 through one wall of the shell Ill.

Located Within the intermediate shell I3, but concentrically spaced therefrom, is one of the two paramagnetic heating elements of the induction heater. This cylindrical shell or member 25 is preferably made of cast iron or soft steel and is formed with heat-radiating fins 26 spaced to form air passages 21 between said members [3 and 25.

The other paramagnetic heating element of the heater, which is also preferably of cast iron or soft steel, is indicated by the numeral 28 and is in the form of a spool, which, at itsends, has outstanding flanges that closely engage the ends of the member 25 leaving an annular space within which is located the electrical induction coil 29. This coil 29 is made of insulated wires and the whole coil is preferably placed withinan outer casing or coating of insulating material 3B. The lead wires 3| to and from the coil are preferably brought in and out through a tube or pipe section 32 that is extended through the heads I 2 and I5, and screwed thereto at adjacent fianged ends of the spool-like element 28. This spool-like element 28 has a large axial air passage 33 and the interior wall of the member 28 is provided with radiating fins 33.

In length, the electro-magnetic heating elements 25 and 28 are less than the space between the head l5 and baiile or partition 2|, so that there i formed an upper distributing chamber 34 and a lower distributing chamber 35.

The cold air under pressure from a suitable outside wall, not shown, will be delivered through the tube 24 through the upper chamber l9 and will be spread out over the head l4 and delivered downward through the annular chamber I8 and completely around the intermediate shell 13. From the annular channel l8 the air initially or slightly warmed will be delivered into the lower chamber 29, and from thence will pass upward through the perforations 23 of head I5, into chamber 35. In chamber 35 the air will be spread out and will pass upward, in part, through the circumferentially spaced passages 21, and in part through the axial passage 33 into chamber 34. From chamber 34 the warmed or hot air will be passed above bafile 2i, and out through the sleeve or neck I 6. The sleeve I6 is shown as internally threaded for application of a hot air delivery pipe or tube, not shown.

The air passed upward through the circumferentially spaced channels 21 will be subjected to heat radiated from the fins 26; and in passing upward through the axial passage 33 the air will be subjected to heat radiated from the internal fins 33'.

In this heater the cold air is progressively warmed or heated as it passes through the heater. Of course, the hottest place is adjacent to the induction heating elements 25 and 28. Nevertheless, heat will be radiated radially outward so that the incoming air will be initially warmed as it passes downward through the annular channel or passage I8. As the air passes upward through a and around the core of the heater, it will receive its final temperature, both by .direct radiation and by contact with the walls and fins of the core. The perforated bottom or head l spreads the air and distributes it within the chamber 35, so that it will be evenly or properly distributed through the axis and around the core. From the chamber 34, the air passes through the perforations 22 and out through the neck 16, as already stated, in final heated condition.

This being an induction heater, the wires or leads 3] will be connected with a suitable source of alternating current; and the coil will be of low resistance.

The inner shell 13 should be of metal so that it will conduct and radiate heat into the annular space H). The body of the outer heating element 25 is spaced from the shell l3, but its radiating fins 25, as stated, preferably have direct contact with the said metallic shell 13. The air inlet to the interior of the shell 13 is through the ports 23 in head 15 and the outlet for the heated air is forced through the perforations 22 of the baiile 2|, and thence out through the tubular sleeve iii. The cold air inlet 24 to the chamber I9 is at the upper end of the heater and the outlet iii for the hot air is also at the upper end of the heater. The air entering cham ber 35 is spread out and properly distributed for passage through the axis of the heating core and around the same through the circumferentially spaced air passages 21. The spacing of the heating core from the heads 24 and I5, as well as from the bafille 2!, is important as is obvious from statements already made.

For convenience in this specification and claims, the term air passages or ports has been used to indicate passages for fluid that is to be heated by the device; but, as already stated, the heater can be used for heating water or liquids.

What I claim is:

1. In an induction heater, a drum-like shell having an inlet passage in one end and an outlet passage in its other end, a paramagnetic heating core enclosed entirely within said drumlike shell, said paramagnetic heating core being in peripheral contact with the inner surface of said shell and being spaced from the ends thereof to provide i'iuid chambers therebetween and the ends of said shell, said paramagnetic heating core com- 4 prising telescopically engaged inner and outer heating elements formed to provide an annular coil space therebetween, an induction coil incorporated in said core between the inner and outer heating elements thereof, the said inner heating element of said paramagnetic core being provided with an axially extended fluid passage connecting the said opposite end chambers of the drum-like shell, the said outer heating element of said paramagnetic core being provided with circumferentially spaced passages connecting the said end chambers of the drum-like shell, an outer drumlike shell spaced from the sides and ends of the aforesaid drum-like shell, said outer shell having a fluid passage therethrough at one end portion to the space between said drum-like shells, and

a fluid conduit leading through the same end portion of the outer shell to the adjacent end chamber of the other shell.

2. In an induction heater, 2. drum-like shell having an inlet passage in one end and an outlet passage in its other end, a paramagnetic heating core enclosed entirely within said drum-like shell, said paramagnetic heating core being in peripheral contact with the inner surface of said shell and being spaced from the ends thereof to provide iiuid chambers therebetween and the ends of said shell, said paramagnetic heating core comprising telescopically engaged inner and outer heating elements formed to provide an annular coil space therebetween, an induction coil incorporated in said core between the inner and outer heating elements thereof, the said inner heating element of said paramagnetic core being provided with an axially extended fluid passage connecting the'said opposite end chambers of the drum-like shell, the said outer heating element of said paramagnetic core being provided with circumferentially spaced passages connecting the said end chambers of the drum-like shell, an outer drum-like shell spaced from the sides and ends of the aforesaid drum-like shell, said outer shell having a fluid passage therethrough at one end portion to the space between said drum-like shells, and a fluid conduit leading through the same end portion of the outer shell to the adjacent end chamber of the other shell, said conduit serving to bind the said shells together.

EINAR G. LOFGREN. 

